During use, fuel injection nozzles of gas turbine engines are known to develop deposits of what is called coke in the fuel passages proximate the engine combustor; i.e. in the fuel discharge passages proximate the nozzle discharge tip that is exposed to the combustor for discharging fuel thereto. The coke deposits are formed proximate the nozzle fuel discharge tip by action of combustor heat on stagnant fuel residing in the fuel passages communicating with the combustor to carbonize the fuel to coke. For example, fuel residing in the primary fuel passages can be carbonized to form deposits of coke after engine shutdown when non-flowing fuel residing in the primary fuel passages is baked by the combustor heat. During engine operation, primary fuel flow through the primary passages is typically continuous such that coking does not occur during engine operation.
On the other hand, fuel in the secondary fuel passages can be carbonized to form deposits of coke during and after engine shutdown. In particular, secondary fuel is sometimes interrupted during engine operation such that there is non-flowing fuel present in the secondary fuel passages. The secondary fuel can be baked by the combustor heat in this situation to form coke deposits. Moreover, fuel residing in the secondary fuel passages also can be carbonized to form deposits of coke after engine shutdown when non-flowing fuel resides in the secondary fuel passages and is baked by the combustor heat to form coke deposits.
The formation of coke deposits in the primary and/or secondary fuel passages proximate the nozzle fuel discharge tip occurs over time and adversely affects performance of the fuel injection nozzle. Moreover, coke deposits also form on external tip surfaces exposed to the engine combustor. As a result, fuel injection nozzles are periodically removed from the engine and subjected to a cleaning operation to remove the coke deposits from the fuel passages.
A typical cleaning procedure heretofore employed involved fixturing a cleaning device on the nozzle fuel discharge tip and submerging the nozzle in an ultrasonically activated bath of cleaning solution such as an caustic aqueous solution. Periodically, the cleaning solution is pumped from the fixture on the nozzle discharge tip toward the fuel inlet fittings of the fuel injection nozzle in a manner that the cleaning solution flows in the opposite direction of normal fuel flow through the nozzle fuel passages. The cleaning solution is formulated to dissolve coke deposits present in the fuel passages. The nozzle can be subjected to a further cleaning in another less caustic solution contained in a separate cleaning tank and finally to a water rinse of the fuel passages in a separate rinsing tank.
The aforementioned cleaning procedure is disadvantageous in several respects. For example, fixturing of the cleaning device on the nozzle fuel discharge tip exposes this critical, close tolerance region of the fuel injection nozzle to possible mechanical damage. Moreover, when the cleaning device is actuated to pump cleaning solution through the fuel passages, the flow of cleaning solution through the primary fuel passages may not be adequate for removal of coke deposits therein as a results of the considerably smaller cross-sectional dimension of the primary passages as compared to the secondary fuel passages. That is, the cleaning solution flows through the larger sized secondary fuel passages preferentially to the smaller primary fuel passages. Inadequate cleaning of the primary fuel passages can result. Furthermore, the cleaning solution is pumped through the fuel passages only from the discharge tip end of the fuel injection nozzle toward the inlet fittings thereof. Unless the fuel injection nozzle is again fixtured to connect the inlet fittings to the cleaning solution source, there is no pressurized cleaning solution flow in the opposite direction. In addition, the cleaning procedure is carried out using a series of separate cleaning tanks for different cleaning solutions that may be employed and separate rinse tanks. This complicates the cleaning apparatus and requires transporting the fuel injection nozzles from one cleaning or rinsing tank to another such that there is excessive handling of the nozzles during the cleaning operation.
It is an object of the present invention to provide a cleaning apparatus and method for cleaning one or more internal passages of an article of manufacture wherein fixturing on a critical, close tolerance region of the article (e.g. on a fuel nozzle tip) during the cleaning operation is avoided.
It is another object of the present invention to provide a cleaning apparatus and method for cleaning one or more internal passages of an article of manufacture wherein adequate flow of cleaning fluid can be provided through differently sized internal passages to provide proper cleaning of all of the passages.
It is still another object of the present invention to provide a cleaning apparatus and method for cleaning one or more internal passages of an article of manufacture wherein flow of cleaning fluid through the internal passages can be reversed.
It is still a further object of the present invention to provide a cleaning apparatus and method for cleaning one or more internal passages of an article of manufacture wherein cleaning and rinsing of the internal passages can be conducted using a common tank or container.